1. Field of the Invention
The present invention relates to a key device having a plurality of peripheral key tops arranged closely around a center key top so that those key tops, when pressed, operate switches and thus serve as push buttons.
2. Description of the Prior Art
FIG. 15 is an exploded perspective view of a conventional key device. The key device 100 has a plurality of peripheral key tops 102 arranged around a circular center key top 101. Below the center key top 101 and the peripheral key tops 102, there are provided push switches (not shown) one for each key top. Each peripheral key as defined in the prior art of the disclosure is in the shape of a circular portion which has an inner circular shape and an outer circular shape. The inner circular shape is adjacent to the circular center key top.
Around the peripheral key tops 102, there is provided a ring-shaped peripheral frame 104 that is fixed to a circuit board (not shown). Each peripheral key top 102 is linked to the peripheral frame 104 by two peripheral hinges 103. Thus, the peripheral key tops 102 are elastically supported so as to be movable up and down.
The center key top 101 has a recessed edge at the top so that it is prevented from dropping off by a panel cover (not shown) with a hole so sized as to cover the shoulder portion 101a, i.e., the lower-step portion, of the center key top 101 and expose the exposed portion 101b, i.e., the upper-step portion, thereof. The center key top 101 is movable up and down thanks to the resilience of the push switch provided below it.
In the key device 100 structured as described above, the center key top 101 can freely move radially and rotate owing to the gap between the exposed portion 101b thereof and the hole of the panel cover. Thus, when operated, the center key top 101 may rotate and incline into a lopsided position. This spoils operability and appearance.
To solve this problem, the applicant of the present invention once proposed, in Japanese Patent Application Laid-Open No. 2001-266697, a key device provided with a supporter for supporting the center key top 101. In this key device, as shown in FIG. 16, below the center key top 101, there is provided a supporter 107 having the same shape as the center key top 101 as seen in a plan view.
Moreover, the center key top 101 is elastically supported by a center hinge 106 that extends circumferentially from the top of the supporter 107. This prevents the center key top 101, located at the center of the peripheral key tops 102 (see FIG. 5), from moving as seen in a plan view, and thus helps achieve satisfactory operability and appearance.
However, in the key device described above, in which the center key top 101 is provided with the supporter 107, the supporter 107 needs to be arranged three-dimensionally with respect to the center key top 101. This complicates the shape of the mold used, and also complicates the molding process, resulting in the comparatively high costs of the key device.
An object of the present invention is to provide a key device that can be produced at lower costs and that offers improved operability and appearance.
To achieve the above object, according to the present invention, in a key device having a plurality of peripheral key tops arranged around a center key top so that the key tops, when pressed, operate switches arranged below the key tops respectively, the center key top is elastically supported by a center hinge extending from a center frame provided around the center key top, and the peripheral key tops are provided above the center frame and are each elastically supported by a peripheral hinge extending from a peripheral frame provided around the peripheral key tops.
Alternatively, according to the present invention, in a key device having a plurality of peripheral key tops arranged around a center key top so that the key tops, when pressed, operate switches arranged below the key tops respectively, the peripheral key tops are each elastically supported by a peripheral hinge extending from a peripheral frame provided around the peripheral key tops, and the center key top is elastically supported by a center hinge that is linked to the peripheral frame by being laid between adjacent ones of the peripheral key tops.
According to the present invention, in either of the key devices described above, the plurality of peripheral key tops may be integrated together into a single ring-shaped member. In this structure, when part of the peripheral key top member is pressed, it inclines and operates one switch.
According to the present invention, in either of the key devices described above, the center hinge may be arranged along the circumference of the center key top. In this structure, the center hinge is given a sufficient length between the ends thereof to make it easy to elastically support the center key top.
According to the present invention, in either of the key devices described above, a cover for covering the center hinge may be formed so as to extend from the surface of the center key top or of the peripheral key tops.
According to the present invention, in either of the key devices described above, the cover may have an edge thereof so formed as to droop down to form an edge wall. In this structure, when pressed, the center or peripheral key tops go down while being guided by the edge wall.